This invention relates to character reading system, and more particularly to a character reading system in which a character written on a sheet is manually scanned to optically read the character.
Most of the conventional devices for reading printed characters or written characters employ intricate scanning means utilizing flying spot scanning tubes or multi-stage registers. Accordingly, the conventional devices are unsatisfactory in that they are intricate in construction and high in manufacturing cost.
In such a conventional device, means such as a pattern matching means is employed. Therefore, if, when an original character pattern is converted into an electrical signal which is stored in a shift register or the like, it is inclined or is moved vertically or horizontally, it is difficult to recognize the character. Accordingly, it is necessary to carry out an intricate preprocess to allow the inclination and position of the character pattern to approach those of a standard pattern before the character recognition. Especially when the horizontal scanning rate is greatly varied, the scanner is not able to achieve the sampling timing synchronization and it is difficult to recognize the character. Thus, where the scanning is carried out manually, the reading of the character is impossible.
Some conventional devices employ histograms as recognition means. However, these devices are still disadvantageous in that characters to be read are limited.
An additional problem encountered in conventional character reading systems is the determination of the order of the detected characters when the direction of scan is varied.
FIG. 1 shows the case in which numerals 1, 2, 3, 4 and 5 on a sheet 31 are read by horizontally moving a sensor 32 along the sheet 31. In a conventional reading system, it cannot be detected whether the numerals are arranged in the order 1, 2, 3, 4 and 5 or in the order 5, 4, 3, 2 and 1. Therefore, in order to overcome this difficulty, the movement direction of the sensor 32 or the sheet 31 is limited to only one direction (of the arrow 33). Furthermore, in reading characters by moving the sensor 32 with the hand, the limitation of the movement direction to only one direction makes the operation rather troublesome or difficult. Therefore, it is necessary to put an English character before a series of numerals as shown in FIG. 2(a), or to place a start mark and an end mark respectively before and after the series of numerals as shown in FIG. 2(b). This is a further drawback accompanying the conventional character reading system.